I vote via Georgia Absentee ballot in every election. It’s not like hanging chads. You’d have to have a major case of Parkinson’s disease to mark something by mistake. It sounds more like they couldn’t scan the ballot for some reason so they have to count it manually. The only way you could really cheat on it is by either willfully miscounting or filling in a choice that was left blank. A willful miscount would be easy to spot in a recount and I doubt there would be enough blank choices to sway anything larger than a local election where a vote or 2 could make the difference.
“A willful miscount would be easy to spot”
I could be wrong about this but don’t the Dominion machines reprint a proper ballot after adjudication? And weren’t there lots of ballets shredded, presumably the dirty marked up ones? So during the recounts there is nothing nefarious to see.